Auxiliary signaling circuits



July 21, 1925.

1,546,427 H. A AFFEL AUXILIARY SIGNALING CIRCUITS Filed May 18, 1921 3 Sheets-Sheet l avwenfo a Jul 21, 1925. 1,546,427

H. AFFEL AUXILIARY SIGNALING CIRCUITS Filed May 18, 1921 3 SheetsSheet 2 @t iIaLg wmwtIg 235 61 0 flaw wig Wk Patented July 21, 1925.

aa zi BUNITED'STATE'S PATENT OFFICE.

HERMAN A. AFFEL, OF BROOKLYH,,NEW YORK, ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

AUXILIARY SIGNALING CIRCUITS.

Application filed Kay 18,

To all whom it may concern:

Be it known that I, HERMAN A. AFrEL, residing at Brooklyn, in the county of Kings and State of New York, have invented certain Improvements in Auxiliary Signaling Circuits, of which the following is a specificat /On.

Tliis invention relates to signalmgsystems, and more particularly to the proyislon of means for transmitting auxiliary signals over long toll wire or carrier telephone 011- cuits.

Where it is desired to transmit auxiliary signals such as ringing signals over long toll wires or over carrier telephone circuits, d fficulty is frequently experienced in transmitting the ringing signals because of the intermediate repeater included at various points in the toll circuitor carrier telephone circuit. It frequently occurs, however, that a number of such circuits parallel each other and terminate at the same points. It is therefore possible to employ an external circuit extending between these points for the trans mission of the ringing or other auxiliary signals.

In accordance with the present lnventlon it is proposed to utilize a carrier telegraph circuit in order to provide signaling channels for the toll lines or carrier telephone circuits paralleling thecarriertelegraph circuit.

lVhile it would be possible to use a separate carrier telegraph channel as the signaling means for each telephone circuit, this method is not desirable, inasmuch as it involves the use of channels inherently capable of transmitting high speed signals for the transmission of the low speed signals involved in ringing and other auxiliary operations. Furthermore, this method would require a maximum amount of apparatus, since essentially a complete carrier transmitting and receiving circuit would be necessary for eachsignaling channel. The method is therefore both uneconomical in the use of the frequency range and thephysical apparatus employed.

Another method would be to use a single carrier telegraph circuit to transmit all of the ringing or other auxiliary signals involved, other channels of such a system being employed if desired for the transmission of telegraph signals in the usual manner. In order that such a single high speed car- 1921. Serial No. 470,593.

rier telegraph channel might serve to transmit the signals of a plurality of telephone line, synchronous distributors would have to be provided at either end of the carrier telegraph channels, so that'the carrier teleboth the methods above referred to, and in 1 a sense may be considered a combination of thet wo. r

The invention may now be more fully understood from the following description when read in connection wit-h the accompanying drawing, in which Figure 1 illustrates one form ofapparatus to be associated with a carrier telegraph channel in order that the channel may serve to transmit the ringing signals for a plurality of telegraph lines, Fig. 2 of which illustrated the circuit connections for associating one of the signaling channels superposed upon a carrier telegraph channel with the corresponding telephone line, and Figs. 3 and 4 of which illustrate modified forms of theinvention.

Referring to Fig. 1, L designates a line circuit which may be employed for thetransmission of carrier currents in a manner well known in the art. As illustrated, the line L terminates at each end in branches including band filters BF and BF, which are selective of the carrier frequencies assigned to a particular telegraph channel. Multiple connections are indicated on the drawing to show the manner in which other channels may be associated with the ends of the line L. In the illustration it is assumed that such other channels may be used for transmitting carrier telegraph signals in the usual manner, and, as this apparatus is well understood and constitutes no part of the present invention, it is not illustrated. The channels involving the filters BF and BF are associated with transmitting and receiving apparatus, whereby these channels may be employed to transmit ringing signals for a number of telephone toll or carrier lines. For this purpose a rotary distributor RD having six segments is provided, and con-.

the several frequencies,

nections from five of the segments lead to the circuit of a vacuum tube oscillator 0, these connections being in turn controlled by the contacts of relays 11, 12, 13, 14, and 15 under the control of transmitting relays T T T T and T The connections from segments include capacity elements C C C (1 .and 0 whereby the frequency of the oscillator may be determined. If'desired, an amplifier A may be inserted between the oscillator and the band filter BF to amplify the carrierfrequencies to be transmitted over the corresponding telegraph channel.

Since in practice the telegraph channel 1s a high speed channel and is therefore designed to transmit a fairly broad range of it is possible to' subdivide the frequency range of the channel between the auxiliary channels provided by the distributor RD, each segment of which controls the transmission of a different frequency. This is possible because the low frequency ringing or auxiliary signals superposed on the several carrier frequencies which may be generated by the oscillator O for transmission over the signal telegraph channel do not produce wide "bands on either side of the individual carrier frequencies gener ated by the oscillator O.

A sixth segment is provided in connection with the distributor RD for controlling the relays 11 to 15 inclusive. The contacts of these relays are so arranged that when the, relays are energized and the armatures drawn up the armatures are locked in the drawn-up position by means of catches upon the armatures of the transmitting relays T to T inclusive. Consequently, upon t e energization of any one of the transmitting relays, as for example the relay T the armature of the corresponding relay 13 is released to close the circuit through the capacity C as soon as the brush arm passes over the third segment. As the brush arm passes over the sixth segment, it energizes relays 11 to 15 inclusive to restore any armatures which may have been released from their attracted positions.

At the receiving station a vacuum tube amplifier A may be associated with the band filter BF and a plurality of tuned circuits 21, 22, 23, 24, and 25 are provided for selecting the several frequencies transmitted over the carrier telegraph channel. Each tuned circuit is associated with a corresponding detecting arrangement as indi-' .cated at D to D inclusive. Receiving relaysfR 'to R inclusive are assoclated with the detectors and respond to the signals detected from the carrier frequencies to control the ringing or other signals at the receiving station.

The manner in which any one of the five auxiliary signaling channels afi'o-rded by the arrangement of Fig. 1 ma beassociated with a correspondin telep one circuit is illustrated in n' Fig. 2 a carrier transmission line is illustrated as being associated through a terminal carrier apparatus CA with a toll line TL. A transmittin relay T, which maybe any one of the re ays T to T,, inclusive of Fig. 1, is bridged across the toll line in order to re spond to rin ing currents incoming from said line,'an a receiving relay R, which may be any one of a series of relays R to R f a system transmitting in the opposite direction from that of Fig. 1, is arranged to control the transmission of ringing current over the toll line TL from its junctlon point with the carrier line.

Further details of the apparatus maybe understood from the dBSCIIPtlOII of the operation as follows: Let it be assumed that a ringing signal is incoming from the line TL and it is desired to transmit this signal to a similar line connected to the opposite end of the carrier circuit CL without transmittingthe signal over the carrier circuit. The incoming ringing signal from the line TL will operate the transmitting relay T. 1

If new it be assumed that the relay T is the transmitting relay T for example, of Fig. 1, thearmature of said relay .will release the armature of the relay 13, which accordin ly retracts so that a connection is established from the terminal of the upper winding of the oscillator 0, over the contact of the relay 13 and through the condenser G to the third segment of the distributor RD. Whenever the brush arm of the distributor passes over the third segment, therefore, a connection will be completed to the lower terminal of the coil of the oscillator O and the oscillator will generate a series of oscillations whose frequency is determined by the capacity C and whose duration is determined by the period of time required for the brush arm to pass over the segment 3. As the brush arm passes over the other segments from 1 to 5 inclusive, the oscillator may transmit other frequencies if any of the remaining relays T to T are actuated.- As the brush arm passes over the segment 6 a circuit is completed from batter through the windings of each of the re ays ll to 15 inclusive, thereby energizing these relays to attract their armatures and .open through the condensers.

The carrier frequenc generated by the oscillator O as the brus ofthe distributor RD passed over the segment 3 is transmitted over the line L and through the band filter BF to the amplifier A. This frequency is selected by the tuned circuit 23 and impressed upon the detector D to operate the receiving relay R at the distant station.

Jun

the circuits Assuming that the" relay R is located at the distant end (not shown) of the carrier line CL of Fig. 2, and assuming further that at the distant station apparatus identical to that illustrated in Fig. 2 is provided, the actuation of the relay R will 0 erate to transmit ringing current to the toll me connected to the distant end of the carrier line in the same manner as is indicated by the relay R in Fig. 2. Consequently the ringing signal incoming from the ine TL is transmitted over the line L of Fig. 1 .to the distant station and from that point trans-' mitted over the toll line associated with the opposite end of the carrier line of Fig. 2.

Fig. 3 illustrates a modified circuit arrangement, in which the ringing or other signals are transmitted by combinations of one or more frequencies simultaneously transmitted, a plurality of oscillators being provided for generatlng the carrier freuencies. As illustrated, three oscillators O and O" are provided, the circuits of these oscillators being controlled by relays 50, 51, and 52, which are connected to three rings of the distributor RD, the distributor in this case being provided with four rings instead of one, as in Fig. 1. The fourth ring of the distributor RD is provided with indlvidual segments connected with the contacts of relays 11 to 17 inclusive, and the contacts of these relays are controlled by transmitting relays T to T inclusive in the same manner as in .Fi 1, so that any particular transmitting re ay may through the distributor RD control the energizatlon of a corresponding combination of the relays 50, 51, and 52. Each transmitting relay is arranged to control a different combination of the relays 50, 51, and 52, so that a difierent combination of frequencies is transmitted by the oscillators O, C) and O.

The receiving apparatus comprises de tectors D, D, and D", each having tuned circuits in their input circuits and each tuned circuit being responsive to one of the frequencies generated by the three oscillators. The detectors control the circuitsof relays R, R, and R" and these relays operate to selectively control the energization of receiving relays R to R inclusive. It will be understood that the relays R to R inclusive are associated with the corresponding telephone circuits in the manner in which the relay R of Fig. 2 is associated with the line TL and that the transmitting relays T to T will similarly be associated with said telephone circuit in the manner in which the relay T is associated with the circuit TL in Fig. 2.

The operation is as follows: A signal operating the relay T for example, causes the armature of the relay 15 to be released. A circuit is thereby completed from battery over the contact of the relay 15, fifth segment of the inner ring ofthe distributor "through the amplifier and band filter to the line L and over said line to the distant station.

The operation of the receiving apparatus I at the distant station may be understood from a description of the operation of the receiv ing apparatus at the station illustrated, in response to a signal transmitted fromthe distant station. Assuming that two frequencies are incoming from the line L and are transmitted into the receiving channel through the band filter and amplifer pro vided therein, the two frequencies will be separated through the tuned circuits into the detectors D and D", thereby actuating the relays, R and R". As a result of the operation of these relays, a circuit is completed from battery, over the front contact of relay R through the winding of relay R over the upper front contact of relay R", and over the back contact of relay R'- to battery. The

receiving relay R is accordingly actuated to transmit the ringing signal to the corresponding telephone line.

Fig. 4 illustrates an arrangement in which the signals are transmitted by a plurality of separate carrier frequencies. In this case, however, instead of three separate oscillators for supplying the carrier frequencies, a single oscillator is employed, and it sends different frequencies successively instead of simultaneously to determine the proper signaling channels. As illustrated, three frequencies are employed to select any one of a combination of eight signaling channels, and a fourth frequency is used as a controlling or trigger frequency to finally transmit the signal determined by the combination of three frequencies previously transmitted. In order to selectively control the oscillator to determine the frequency generated, four capacities C, O, C and C are provided, and the selective inclusion of one of these capacities in the circuit of the oscillator O is under the joint control of the transmitting relays T to T inclusive and the associated relays 11 to 18 inclusive. The rotary distributor RD is interposed between the capacities and the relays to time the connection of the capacities and thereby time the transmission of the frequencies. The distributor RD in this case is provided with two rings, the inner of which has nine segments, eight corresponding to the individual transmitninth being for the purpose of restoring the plete the connection of these capacities to the oscillator over the brush arm of the distributor.,

The receiving apparatus comprises four detectors D, D, D and D"'.. The detectors D, D and D5, control three relays R, R and R, whose armatures when attracted are held in attracted position by locl ing engagement with the armatures, of auxiliary relays R, ,R, and R and R fourth detector D controls a relay-Rf, which at its upper contact is arranged to complete the circuit selectively set up by the relays R, R, and R through one of the receiving relays R, to R inclusive. At its lower front contact relay R is arranged when energized to complete a circuit to charge up a condenser 40 included in circuit with the relays R R and R The impulse of current in charging the condenser does not actuate these relays, as a resistance 41 is included in the circuit. When the armature of the relay falls off, however, the condenser is permitted "to discharge through the relays over a path independent of the resistance 41, thereby actuating the relays R R R and R to restore the contacts of the selecting relays R, R and R;

The operation is as follows: Assuming that a ringin sigpal comes in from the telephone line wit w ich the relay T, is associated, said relay is energized to attract its armature, thereb permitting the armature of the relay 15 to all oil and establish a connection from the upper terminal of the windingof the oscillator 0 over said contact to the fifth segment of the inner ring of the distributor RD. When the brush arm of the distributor passes over this segment, the circuit thus prepared is completed successively over the first segment of the corresponding group of four in the outer ring, through the condenser C to the lower terminal of the winding of the oscillator 0, over the third segment of the group through the capacity C", and over the fourth segment of the group, and through the capacity C. The oscillator is therefore caused to oscillate successively at the frequencies determined by the capacities G, C and C', the oscillator being, however, inactive at the moment the brush arm passes over the second segment of the fifth group in the outer ring of the dis tributor, since this segment is for the combination under consideration unconnected with the capacity C. The three fre uencies successively generated by the 030i ator O The " order to transmit the signal in the reverse direction; The three frequencies generated are received from the line L and transmitted through the band filler and amplifier of the receiving channel. At this point they are selected by the tuned circuits associated with the input sides of the detectors, and are therefore impressed upon the detectors D,

D and D .The detectors D and D" actuate the relays R and R" to shift their armatures from their back contacts to their front contacts in which position they are locked by the armatures of the relays R R and B In response to the fourth frequency the detector D' actuates the relay R' which, at its upper contact, completes a circuit from battery over said upper contact, over the upper back contact of. relay R, upper front contact of relay B", through the winding of receiving relay R and over the front contact of relay R, back to battery. Relay R is thereby energized and transmits a signal to the corresponding telephone line. At the same time the condenser 40 is being charged over the lower front contact of the relay R through the high resistance 41, which prevents the actuation of rela s R R R and R As soon as tie impulse through the relay R ceases, however, with the cessation of the fourth or trigger frequency the lower armature of the relay R', in falling off, completes a circuit where. by the condenser 40 discharges over a circuit independent of the resistance 41 and through the windings of relays R R R and R These relays are accordingly energized to release the armatures of the relays R, R and R", so that the circuit is restored to normal ready for another selection.

It will be obvious that the general principles herein disclosed may be embodied in many other organizations widely difierent from those illustrated without departing from the spirit of the invention as defined in the following claims.

. What is claimed'is:

1. In a transmission system a plurality of transmission circuits, an auxiliary circuit common to said transmission circuits over which signals originating at 'one end of any one of said transmission circuits may be transmitted to actuate corresponding signaling means associated with the other end of the corresponding circuit, means to translate transmission circuits, an auxillary circuit common to said transmission circuits over which signals originating at one end of any one of said transmission circuits may be transmitted to actuate corresponding signaling means associated with the other end of the corresponding circuit, means to translate said signals into combinations of different carrier frequencies for transmission over said auxiliary circuit, and. integrating detectors at the distant station for translating the various combinations of carrier frequencies into signals corresponding to the original signal.

3. In a transmission system a plurality of transmission lines, an auxiliary signal circuit common to said lines, a distributing arrangement for transmitting signals originating with any of said lines to said auxiliary line, means associated with said distributing apparatus for tranlating said signals into carrier frequencies for transmission over said auxiliaryline, means at the distant end of said auxiliary line for selecting the carrier frequencies and translating them into signals corresponding to the signals originating with the lines at the transmitting station, and means for impressing said signals upon the corresponding line at the receiving station.

4. In a transmission system a plurality of transmission lines, an auxiliary signal circuit common to said lines, a distributing arrangement for transmitting signals originating with any of said lines to said aux1li ary circuit, means associated with said distributor for translating the signals incoming from any of said transmission lines intocombinations of carrier frequencies for transmission over said auxiliary circuit to a distant receiving station, means at the receiving station for selectin said frequencies and translatin the combinations into signals correspon ing to the signals originating at the transmitting station, and means for impressing said signals upon the corresponding transmission lines at said transmitting station.

5. In a transmission system a plurality of transmission lines, an auxiliary signal circuit common to said lines, a distributing arrangement for transmitting signals originating with any of said lines to'said auxiliary circuit means associated with said dis tributor for translating the signals originating with any of said transmission lines into carrier frequencies for transmission over said auxiliary circuit to a distant receiving station, means at said distant station for translating said carrier frequencies into signals corresponding to the original signals at the transmitting station, and means for selectively transmltting said si als'to the l ne corresponding to that wit which the signals originated.

6. In a transmission system a plurality of transmission lines, an auxiliary signal circuit common to said lines, a distributin arrangement for transmitting signals originating with any of said lines to said auxillarl circuit, means associated with said distributor for translating signals originating with any of said lines into combinations of carrier frequencies for transmission over said auxiliary circuit to a distant receiving station, selective means at said distant recelving station responsive to combinations of carrier frequencies to translate said combiassociated with each transmission line responsive to signals originating with said lines, a rotary distributor associated with said lines, said distributor operating in conjunction with said relays to control the transmission of signals from. said lines over said common signaling circuit, means assoclated with said rotary distributor for translatmg said signals into carrier frequencies for transmission over said auxiliary signal circuit to a distant receiving station, and means at said distant receiving station for translating said carrier frequencies into slgnals corresponding to the original si als.

8. In a transmission system a pluraht of transmlssion lines, an auxiliar signa ing circult common to said lines, slgnal relays associated with each transmission line responsive to signals originating with said llnes, a rotary distributor associated with said lines, said distributor operating in conjunction with said relays to control the transmission of signals from said lines over said common signaling circuit, means associated with said rotary distributor for translating said signals into carrier frequencies for transmission over said auxiliary signal circuit to a distant receiving station, means at said distant receiving station for translating said carrier frequencies into signals corresponding to the orlglnal signals,-

and means for selectively transmitting said signals to the lines corresponding to the lines with which the signals originated.

9. In a transmission systems. plurality of transmission lines, an auxiliary signaling nations into signals corresponding to the circuit common to said lines, signal relays associated with each transmission line responsive to signals originating with said lines, a rotary distributor associated with said lines, said distributor operating in conjunction with said relays to control the transmission of signals from said lines over said common signaling circuit, means associated with said distributor for translating said signals into combinations of carrier fre-, quencies for transmlsslon over said auxiliary signaling circuit to a distant receiving station, and means at said distant receiving station for selectively translating said combinations of frequencies into signals corresponding to the original signals.

10. In a transmission system a plurality of transmission lines, an auxiliary signaling circuit common to said lines. signal relays associated with each transmission line responsive to signals originating with said lines, ,a rotary distributor associated with said lines, said distributor operating in conjunction with said relays to control the transmission of signals from said lines over said common signaling circuit, means associated with said distributor for translating said signals into combinations of carrier frequencies for transmission over said auxiliary signaling circuit to a distant receiving station, means at said distant receiving station for selectively translating said combinations of frequencies into signals corresponding to the original signals, and means for selectively impressing said signals upon the lines corresponding to the lines with which the signals originated.

In testimony whereof, I have signed my name to this specification this 16th day of May 1921.

HERMAN AFFEL. 

